Then Internet Explorer (js debug enabled) decides it was the right time for firing fire some fancy javascript errors, like "AJAX Framework failed to load....". No problem, back to fixer mode... and this snippet is the final, working piece of snippet art:

Basically it intervenes at a specific part of the Request handle (AfterProcess) and just if a certain header is found then excludes the AJAX web services from the search, so they can be dealt with in the classic fashion.